The present invention is generally directed to free radical initiated monomer polymerization processes for the formation of resin particles. More specifically, the present invention is directed to polymerization processes wherein monomer polymerization and particle aggregation can be achieved simultaneously under controlled monomer excess feed or "flood" feed conditions to provide monodisperse resin particles and resin particle aggregates thereof with a volume average diameter size range of, for example, from about 1 to about 10 micrometers.
The composition and processes of the present invention enable, in embodiments: emulsifier free emulsion polymerization processes; monodisperse resin particles or resin particle aggregates within an average diameter size range of, for example, from about 1 to about 3 micrometers; monodisperse resin particles or resin particle aggregates with geometric particle size distributions below about 1.05, for example, of from about 1.01 to about 1.02, and d.sub.w /d.sub.n values less than about 1.01; resin particles and particle aggregates which are suitable for use in dry and liquid developers and toner for printing applications; and resin particles and resin particle aggregates which can be grown, or increased in size if desired, to larger average particle sizes.
There are known methods for directly preparing resin particles from monomers, including dispersion polymerization, encapsulation, emulsion polymerization, and emulsion-aggregation. The product particles generally may be optionally colored during or subsequent to particle formation to afford "in-situ" or "chemical" toners. These methods possess unique advantages and disadvantages including: cost; ease of use; product contamination and purification considerations; environmental and waste concerns; reliability in producing product particles with desired physical or chemical properties, such as particle size range, particle size distribution, color, surface roughness or smoothness, particle-particle flowability, blocking temperature, melt flow rheology, chargability, conductivity, and the like characteristics.
The present invention provides, in embodiments, flood feed free radical polymerization processes which can conveniently afford well defined larger sized aggregated resin particles, greater than, for example, about 0.5 microns, for example, from about 1 to about 20, and preferably from about 1 to about 10 microns, and which resin particles are believed to arise from concurrent surfactant-free monomer polymerization and controlled particle aggregation.
The aforementioned and other advantages are achievable with the resin particles compositions and processes of the present invention. The compositions and processes of the present invention are useful in many applications including printing, for example, ink jet and electrostatographic such as in xerographic printers and copiers, including digital systems.